Victoria Azarenka (Current rank -- No. 1): If you asked me a year ago about Azarenka, I would have said I knew she was good. I just didn't know she was this good. The career accomplishments of Maria Sharapova and Serena Williams overshadowed Azarenka's surge to the top this year, so it's easy to forget that the 23-year-old went on a 26-match winning streak and looked unbeatable through the first quarter of 2012. Can she replicate that success? Probably not. Azarenka is in the same boat Novak Djokovic was last year, where expectations have to be tempered given their breakout years.

But one thing made clear toward the end of the season was that Azarenka is for real. It would have been tempting to dismiss her undefeated first quarter as taking place during a time when Williams wasn't exactly at her best. Yet Azarenka showed she had closed the gap in pushing Serena deep into the third set at the U.S. Open and again playing her tough at the WTA Championships in Istanbul. She's already demonstrated that she can beat Sharapova regularly on hard courts. If Azarenka can prove the same against Serena in 2013 -- she's shown signs of getting closer -- she can put all the questions to rest about her legitimacy as a No. 1. Verdict: Hold.

Maria Sharapova (No. 2): Sharapova has two problems to solve, one of which is doable, the other less so. She failed to prove she could beat Azarenka on outdoor hard courts in 2012, a fact that derailed much of her season. Azarenka demolished her in the final of the Australian Open and Indian Wells, and then nipped her in a hotly contested three-setter in the U.S. Open semifinals. If those matches go the other way, then we're looking at Sharapova at No. 1. But they didn't, and the Russian has to get over that in 2013. The other obstacle? Well, that's Serena, and Sharapova has yet to make inroads. Their WTA Championships final was the best Sharapova's played Williams in years, losing 6-4, 6-3.

Could Sharapova get to No. 1 and win another major? Absolutely. I think she's got a few more in her. But she'll have to get through Azarenka and Williams to do it. Tough ask. Verdict: Hold.

Serena Williams (No. 3): It doesn't need to be said again, but I'll say it again: If she's healthy and motivated, Serena is the best female tennis player in the world. She proved this year that age doesn't matter -- she dominates. Once she found her form at Wimbledon, the rest of her year was one-way traffic. She lost only one match after her shocking loss to Virginie Razzano at the French Open, and that was arguably a tank job against Angelique Kerber in Cincinnati.

Given her relatively dismal results in the first half, Williams should overtake Sharapova and Azarenka to assume No. 1 by the time Wimbledon rolls around, if not as early as the Australian Open. The question is whether, once she's reached that level of domination, her hunger will remain. Williams has always been a better underdog than favorite, and once all the metrics point to her as being the best, will she still strive to be? I think she will, for no other reason than age gives you perspective. Serena must know that her time in the sport is dwindling. I wouldn't put it past her to win the Australian Open and Roland Garros, thus completing the Serena Golden Slam. Verdict: Buy.

Agnieszka Radwanska (No. 4): She had a tremendous year, buoyed by her title in Miami and appearance in the Wimbledon final. But much like Sharapova, Radwanska has to prove she can beat Azarenka before we can even address whether she's a legitimate top-three prospect. Verdict: Hold.

Angelique Kerber (No. 5): I'm still trying to figure out how Kerber had the year she had, notching 60 wins in 82 matches. Her physical and mental resiliency was remarkable for a player who had never played that many matches at that level in a year. I hate to be a party-pooper, but I'm just not convinced Kerber can do it again. In her semifinal and quarterfinal runs at Wimbledon and the French Open, respectively, the German benefited from a wide-open draw. A top-five finish was the result of an amazing effort in 2012. I'm just not sure she can replicate it. Verdict: Sell.

Sara Errani (No. 6): To say Errani's 2012 was a breakout year would be an understatement. A French Open final and a U.S. Open semifinal were the highlights, with four titles to boot. Can Errani even equal her 2012 results next year? She'll need a whole lot of luck. Her success at the French and U.S. Opens was due in large part to a draw that broke open after a series of early-round upsets. Verdict: Sell.

Li Na (No. 7): She's fit, motivated under new coach Carlos Rodriguez and in the waning years of her career. Li, 30, knows she doesn't have much time left. She'll try to make the most of it. If there's a player I would back to make a surge in 2013, it's her. Verdict: Buy.

Petra Kvitova (No. 8): At her best, she's second to no one but Williams, and even then there's an argument to be made that Kvitova might have more power and variety. At her worst, Kvitova rarely looks like a top-30 player, spraying balls everywhere and appearing sluggish and lead-footed. Given that range, Kvitova's a tough call as 2013 approaches. So much is dependent on her health and fitness, two things that failed her in 2012. But if you're valuing her commensurate with the eighth-ranked player, she's still a buy. Verdict: Buy.

Sam Stosur (No. 9): Stosur looked burned out by the time 2012 ended, frustrated with herself and her game through the WTA Championships. That image makes it easy to forget she made the semifinals of the French Open for the third time in four years and came so close to knocking off Azarenka at the U.S. Open in one of the best matches of the year. In fact, Stosur's 2012 was full of close calls. She lost 7-5 to Sharapova in the third set of the Stuttgart semifinals, 8-6 in a third-set tiebreaker to Lucie Hradecka in the Madrid quarterfinals, 6-4 in the third to Venus Williams in the Cincinnati quarterfinals, and so on. There's no reason to think she can't turn around those matches in 2013. Verdict: Buy.

Caroline Wozniacki made the second week of one major -- the Australian Open -- in 2012. (Carlos M. Saavedra/SI)

Caroline Wozniacki (No. 10): Wozniacki is much too talented to be ranked this low. A crisis of confidence torpedoed her year, and if it wasn't for a late push through the fall, the Dane wouldn't even be in the top 10. That's a dramatic fall for a woman who began the year No. 1 with a two-year reign at the top. Her titles in Seoul and Moscow have to build her confidence going into 2013, and I suspect she'll be back in the top five by year's end. Verdict: Buy.

Quick hits on the rest:

Maria Kirilenko (No. 14): She was one of my players to watch going into 2012, and her progress continues to impress. If she can maintain some level of consistency, Kirilenko is a top-10 player. She just needs to embrace her variety. Verdict:Buy.

Varvara Lepchenko (No. 21): After solidifying her ranking on clay when she made the semifinals of Madrid and the fourth round of the French Open, Lepchenko tailed off at the end of the season. I'm just not sure she has the weapons to be a mainstay in the top 20. Verdict:Sell.

Hsieh Su-Wei (No. 25): Much like baseball pitchers through the batting order, will her crafty slice-and-dice game succeed the second time around? Hsieh made a move up the rankings in large part because of her success in the ITF circuit. Not sure that will work now that she has to face the elite. Verdict:Sell.

Yaroslava Shvedova (No. 29): She has the talent and plenty of room to excel in the rankings. She may not be able to equal her French Open quarterfinal or Wimbledon fourth round, but she's good enough to pick up those points elsewhere. I don't know if she's top 20, but Shvedova's good enough to hold firm in the top 30. Verdict:Hold.

Urszula Radwanska (No. 31): There's lots to like about the younger Radwanska, who may not have the touch or creativity of Agnieszka, but plays a more traditional baseline game. Verdict: Buy.

Christina McHale (No. 33): McHale contracted mono at the end of the year, which could be a mere blip in her career or a complete derailment. If she's healthy, I still like the 20-year-old American's potential. Verdict: Buy.

Francesca Schiavone (No. 35): At 32 after a 2012 to forget, I'd be shocked if Schiavone was still on tour this time next year. Verdict:Sell.

Anastasia Pavlyuchenkova (No. 36): She's still young, but Pavlyuchenkova, 21, already feels like a bust. The Russian has tremendous ball-striking, but until she commits to her fitness and footwork to, you know, actually get into position to hit the ball, she's risky. Verdict:Sell.

Sabine Lisicki (No. 37): A Wimbledon stalwart, Lisicki is just too good to be ranked this low. The German has proved she can win titles on any surface, but in a year when her peers -- including Azarenka and Kvitova -- completely passed her by, who knows what 2013 will bring. I'm banking on a hungry and motivated Lisicki. Verdict:Buy.

Sloane Stephens (No. 38): For two straight years, Stephens has shown she loves the big stage. Now it's time to apply that same work ethic and focus for the smaller tournaments, where points are there for the taking. Stephens, 19, may just be the most gifted athlete behind Williams, yet that ability has allowed her to be lazy in her footwork. There's nothing but upside. She just needs time to grow. Verdict:Buy.